# debug

The debug skill gives your agent a fixed order for bug work: reproduce, test hypotheses, find the root cause. Useful when a stack trace or a failing test lands on you.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 436 installs · ★ 218
- Author: pproenca
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/pproenca/dot-skills/tree/HEAD/skills/.curated/debug/SKILL.md
- Updated: 2026-08-15
- HTML: https://affpapa.org/en/nevibecode/skills/pproenca-debug

## What it does

The `debug` skill is a rule set for debugging: 54 rules in 10 categories, sorted by impact. The top two categories are marked CRITICAL, problem definition and hypothesis-driven search. Then come observation techniques, root cause analysis, tool mastery, triage, common bug patterns, fix verification, anti-patterns and prevention.

Each rule has a short name and a prefix: `prob-reproduce-before-debug`, `hypo-binary-search`, `rca-five-whys`, `anti-shotgun-debugging`. They live as separate files under `references/`, with the full compiled version in `AGENTS.md`. The method draws on Andreas Zeller's "Why Programs Fail" and academic debugging curricula.

Worth installing if your agent patches bugs by guesswork, which is exactly what `anti-shotgun-debugging` targets. It runs on Claude, Codex, Cursor, GitHub Copilot, Gemini CLI and OpenCode, and lands in that platform's skills directory, for example `~/.claude/skills/debug/SKILL.md`.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill debug -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/debug/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/debug/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill debug -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/debug/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill debug -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/debug/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install pproenca/dot-skills debug
```

2. **Manually: put the files in place**
- File: `.github/skills/debug/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill debug -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/pproenca/dot-skills --path skills/.curated/debug
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/debug/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill debug -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/pproenca/dot-skills/tree/HEAD/skills/.curated/debug/SKILL.md

## When to use it
- reproduce a bug before touching the code
- cut a failure down to a minimal case
- separate symptoms from causes
- find the last known good state
- verify a fix without shipping a regression

## Example prompts
- walk through this stack trace using the debug method
- this test only fails in CI — find the root cause
- build a minimal reproduction for this bug

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 51db0f5c648b75fd.

BEGIN THIRD-PARTY FILE 51db0f5c648b75fd
```text
---
name: debug
description: Comprehensive debugging methodology for finding and fixing bugs (formerly debugging). This skill should be used when debugging code, investigating errors, troubleshooting issues, performing root cause analysis, or responding to incidents. Covers systematic reproduction, hypothesis-driven investigation, and root cause analysis techniques. Use when encountering exceptions, stack traces, crashes, segfaults, undefined behavior, or when bug reports need investigation.
---

# dot-skills Debugging Best Practices

Comprehensive debugging methodology guide for software engineers, containing 54 rules across 10 categories prioritized by impact. Based on research from Andreas Zeller's "Why Programs Fail" and academic debugging curricula.

## When to Apply

Reference these guidelines when:
- Investigating a bug or unexpected behavior
- Debugging code during development
- Code produces wrong results or crashes
- Performance issues need root cause analysis
- Triaging incoming bug reports and prioritizing fixes
- Conducting root cause analysis for incidents
- Reviewing debugging approaches or code for common bug patterns

## Rule Categories by Priority

| Priority | Category | Impact | Prefix |
|----------|----------|--------|--------|
| 1 | Problem Definition | CRITICAL | `prob-` |
| 2 | Hypothesis-Driven Search | CRITICAL | `hypo-` |
| 3 | Observation Techniques | HIGH | `obs-` |
| 4 | Root Cause Analysis | HIGH | `rca-` |
| 5 | Tool Mastery | MEDIUM-HIGH | `tool-` |
| 6 | Bug Triage and Classification | MEDIUM | `triage-` |
| 7 | Common Bug Patterns | MEDIUM | `pattern-` |
| 8 | Fix Verification | MEDIUM | `verify-` |
| 9 | Anti-Patterns | MEDIUM | `anti-` |
| 10 | Prevention & Learning | LOW-MEDIUM | `prev-` |

## Quick Reference

### 1. Problem Definition (CRITICAL)

- `prob-reproduce-before-debug` - Reproduce the bug before investigating
- `prob-minimal-reproduction` - Create minimal reproduction cases
- `prob-document-symptoms` - Document symptoms precisely
- `prob-separate-symptoms-causes` - Separate symptoms from causes
- `prob-state-expected-actual` - State expected vs actual behavior
- `prob-recent-changes` - Check recent changes first

### 2. Hypothesis-Driven Search (CRITICAL)

- `hypo-scientific-method` - Apply the scientific method
- `hypo-binary-search` - Use binary search to localize bugs
- `hypo-one-change-at-time` - Test one hypothesis at a time
- `hypo-where-not-what` - Find WHERE before asking WHAT
- `hypo-rule-out-obvious` - Rule out obvious causes first
- `hypo-rubber-duck` - Explain the problem aloud

### 3. Observation Techniques (HIGH)

- `obs-strategic-logging` - Use strategic logging
- `obs-log-inputs-outputs` - Log function inputs and outputs
- `obs-breakpoint-strategy` - Use breakpoints strategically
- `obs-stack-trace-reading` - Read stack traces bottom to top
- `obs-watch-expressions` - Use watch expressions for state
- `obs-trace-data-flow` - Trace data flow through system

### 4. Root Cause Analysis (HIGH)

- `rca-five-whys` - Use the 5 Whys technique
```
END THIRD-PARTY FILE 51db0f5c648b75fd

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